I purchased a "mantle shelf" from Michael's craft store. Next, with the help of my dad, I cut a 2x12 piece of wood to the same width as the shelf. Then we tiled it. The tiles on the front have little waves in them.
Then Shawn and I went to the hardware store. We found that the fancy trim that you put around doors was just the right size for my fireplace. My mother-in-law and my neighbors helped me to put together two L-shaped pieces of wood that spanned the area between the shelf and the hearth. The door moldings glued perfectly to the front of the L-pieces.
I dremmeled diamond-shaped squares to fit the turtle tiles. The extra piece of door moldings fit nicely under the shelf, but it was very difficult to affix. I ended up having to bracket it to the mantle.
After much spackling, I painted the whole thing (except the back) white.
The candle holder was a design that my mother-in-law found in an issue of Sunset Magazine. It is made by cutting, sanding, and bending aluminum flashing into the right shape. I had to scale it down a bit, because it was designed for a real fireplace.
The mantle is decorated for Christmas (sans stockings - I didn't want to catch them on fire). Behind the pine, you may be able to see the model of the Nautilus Shawn helped make for Disneyland. They used to be sold in the Disneyana store on Main Street.
The print above the fireplace, "Contemplating Atlantis," is by our friend, Sue Dawe.